type floatInfo … var float32info … var float64info … // FormatFloat converts the floating-point number f to a string, // according to the format fmt and precision prec. It rounds the // result assuming that the original was obtained from a floating-point // value of bitSize bits (32 for float32, 64 for float64). // // The format fmt is one of // - 'b' (-ddddp±ddd, a binary exponent), // - 'e' (-d.dddde±dd, a decimal exponent), // - 'E' (-d.ddddE±dd, a decimal exponent), // - 'f' (-ddd.dddd, no exponent), // - 'g' ('e' for large exponents, 'f' otherwise), // - 'G' ('E' for large exponents, 'f' otherwise), // - 'x' (-0xd.ddddp±ddd, a hexadecimal fraction and binary exponent), or // - 'X' (-0Xd.ddddP±ddd, a hexadecimal fraction and binary exponent). // // The precision prec controls the number of digits (excluding the exponent) // printed by the 'e', 'E', 'f', 'g', 'G', 'x', and 'X' formats. // For 'e', 'E', 'f', 'x', and 'X', it is the number of digits after the decimal point. // For 'g' and 'G' it is the maximum number of significant digits (trailing // zeros are removed). // The special precision -1 uses the smallest number of digits // necessary such that ParseFloat will return f exactly. func FormatFloat(f float64, fmt byte, prec, bitSize int) string { … } // AppendFloat appends the string form of the floating-point number f, // as generated by [FormatFloat], to dst and returns the extended buffer. func AppendFloat(dst []byte, f float64, fmt byte, prec, bitSize int) []byte { … } func genericFtoa(dst []byte, val float64, fmt byte, prec, bitSize int) []byte { … } // bigFtoa uses multiprecision computations to format a float. func bigFtoa(dst []byte, prec int, fmt byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte { … } func formatDigits(dst []byte, shortest bool, neg bool, digs decimalSlice, prec int, fmt byte) []byte { … } // roundShortest rounds d (= mant * 2^exp) to the shortest number of digits // that will let the original floating point value be precisely reconstructed. func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) { … } type decimalSlice … // %e: -d.ddddde±dd func fmtE(dst []byte, neg bool, d decimalSlice, prec int, fmt byte) []byte { … } // %f: -ddddddd.ddddd func fmtF(dst []byte, neg bool, d decimalSlice, prec int) []byte { … } // %b: -ddddddddp±ddd func fmtB(dst []byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte { … } // %x: -0x1.yyyyyyyyp±ddd or -0x0p+0. (y is hex digit, d is decimal digit) func fmtX(dst []byte, prec int, fmt byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte { … }
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